The present invention relates to a brake arrangement intended for a number of threads or yarns which can be fed in or to a textile machine. One example of a textile machine which may be mentioned is a weaving machine, and for further examples reference may be made to the TM 300 and TM 400 machines sold commercially by TEXO AB, Sweden. The feed threads or yarns are assumed to have substantially identical diameters.
1. Prior Art
Brake arrangements for different types of threads and yarns for use in textile machines are already well known. For example, it is already known to use brake arrangements with plates or the like pressed against each other and with a thread or a yarn lying between them, the press force of these plates thus being used to determine the braking speed. Reference may be made here to what is generally known in the field of textile machines and thread control wheels. The brake arrangement is intended to be able to define, inter alia, the thread or yarn tensioning in the threads or yarns leaving the brake arrangement.
2. Disclosure of the Invention
In various situations there is a need to be able to exert a braking action on a number of parallel weft or warp threads, yarns, etc. In this regard, it is essential that the effected braking force is identical on all the threads so that some threads are not braked more strongly than others, or vice versa. The aim of the invention is to solve this problem among others.
It is also important that the brake can be designed with technically simple means and that it is still technically reliable. In connection with brakes of this type, there is in some cases a further requirement of being able to vary the braking force in steps or continuously and, if appropriate, for this to be controlled from a superior or subordinate control unit in the actual machine. Moreover, the brake arrangement should not exert inappropriate stresses on the threads or yarns resulting in damage or discolouring of the latter. The brake arrangement must therefore be gentle on the threads or yarns involved. The invention aims to solve this set of problems too.
The feature which can principally be regarded as characterizing the novel brake arrangement is that it comprises two units which have thread or yarn parts lying between them and which are pressed towards each other by actuating members, which units cooperate with the thread or yarn parts via two surfaces made of smooth material, situated or directed opposite each other and set substantially parallel by the cooperation with the thread or yarn parts. A further feature of the subject of the invention is that the actuating member or actuating members is (are) arranged to exert, via the units, press forces on the thread or yarn parts which are substantially identical, on the one hand, on the different thread or yarn parts and, on the other hand, along at least part of the length of the respective thread or yarn part.
In one illustrative embodiment of the concept of the invention, the unit consists of or comprises two glass panels. Alternatively, the units can be made of smooth plastic material, for example polyethylene. In one illustrative embodiment, the opposing surfaces can have depressions or grooves extending in the longitudinal direction of the thread or yarn parts. At the inlet opening to the brake arrangement, the units are preferably provided with bevels in the material in order to prevent the threads or yarns being cut into. The threads or yarns can also be provided with a smooth outer surface. The actuating member can be made adjustable in order to obtain various desired press forces for the thread or yarn parts. In one embodiment, the actuating member can consist of or comprise permanent magnets applied on the outside of both units, from which the units obtain magnetic holding forces which generate the said press forces on the thread or yarn parts. In a further embodiment, the actuating member can consist of or comprise electromagnets, which can be controlled by electric signals for obtaining different press force levels. In a further illustrative embodiment, the actuating member can comprise mechanical weights, springs, etc., which effect the said pressing forces.
By means of what has been proposed above, an economically advantageous brake arrangement is obtained which can be mass-produced and used widely in the textile industry. In one embodiment, the brake arrangement is made especially simple and can be designed, for example, with glass panels and permanent magnets, the number of which determines the brake force exerted or the press forces exerted. The panels thus consist of smooth material which from the point of view of slide is compatible with the outer material of the threads or yarns which in this case, as it consists of or comprises plastic material, results in an advantageous drawing-through and braking function in the brake arrangement. The units can, if appropriate, be assigned a cooling function which reduces the temperature at high run-through speeds of the threads or yarns.
The novel arrangement can function as a thread-tensioning or yarn-tensioning member for the thread or yarn parts issuing from the brake arrangement in question, in which case the thread or yarn tensions can be determined with great precision and can in addition be varied if so desired.